TAXONOMY AND DEPTH DISTRIBUTION OF PROTEOLYTIC BACTERIA
ISOLATED FROM WATER OF THE RIO GRANDE RISE REGION, SOUTH
ATLANTIC
da Silva, M. A. C.1*; Verdegal, R. O.1; Zirke, B.1; Delabary, G. S.1; da Veiga, C. H. 1; Lima, A.
O. S.1.
1
Centro Tecnológico da Terra e do Mar, Universidade do Vale do Itajaí, Santa Catarina, Brasil.
*e-mail: [email protected]
Proteases are hydrolytic enzymes that act on peptides and are important for the normal
functioning of cells. These molecules are widely distributed in marine bacteria, including
intracellular and extracellular types. Besides their biological importance for the bacterial cell,
proteases can also be biotechnologically applied to wastewater treatment, to the production of
detergents and animal feed. Several marine bacteria are reported as capable of producing
proteases, including strains isolated from different depths of oceanic regions. In this context,
the present work aimed to analyze the taxonomic composition and depth distribution of
proteolytic bacteria from water samples of the Rio Grande Rise Region, South Atlantic. One
hundred and four strains of marine bacteria were tested in triplicates for their proteolytic
activity on marine agar plates supplemented with skim milk. Twenty-four percent of the
strains tested were proteolytic. The frequency of proteolytic bacteria was higher at the
thermocline zone, followed by the maximum depth zone (at the bottom of the water column).
These are zones with higher organic matter concentration, as a function of the primary
production (at the thermocline) and the influence of sedimentary organic matter (at the
maximum depth), which could explain this distribution pattern. The lowest frequency of
proteolytic bacteria was observed at the limit of the euphotic zone. The proteolytic bacteria
belonged to nine different species of five bacterial classes. The class Bacilli was the best
represented among the proteolytic bacteria, with five strains belonging to the species Bacillus
stratosphericus. G am m aprot eobact eri a w as repres ent ed by t hree s t rai ns of
Pseudoalteromonas mariniglutinosa, and Flavobacteriia included three strains of
Zunongwangia profunda. The other species were represented by a single strain each and
include the classes Alphaproteobacteria and Actinobacteria. The strain Salinicola salarius
LAMA 918 was the most active among the bacteria tested. These results indicate that
proteolytic bacteria are diverse and are not equally distributed in marine pelagic
environments.
Palavras-chaves: Proteolytic bacteria, South Atlantic Ocean, depth distribution.
Área de conhecimento: Microbiologia Ambiental e Agrícola